f3eade2f62
Drop the AGPL license in favor of a source-available license. See the blog post [1] for details. [1] https://www.scylladb.com/2024/12/18/why-were-moving-to-a-source-available-license/
93 lines
3.3 KiB
C++
93 lines
3.3 KiB
C++
/*
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* Copyright (C) 2015-present ScyllaDB
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*
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* Modified by ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: (LicenseRef-ScyllaDB-Source-Available-1.0 and Apache-2.0)
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*/
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#pragma once
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#include <seastar/core/shared_ptr.hh>
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#include "seastarx.hh"
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#include <optional>
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#include <vector>
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#include <stddef.h>
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#include "cql3/expr/expression.hh"
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class schema;
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namespace cql3 {
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class column_identifier;
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class column_specification;
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namespace functions { class function_call; }
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/**
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* Metadata class currently holding bind variables specifications and
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* `function_call` AST nodes inside a query partition key restrictions.
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* Populated and maintained at "prepare" step of query execution.
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*/
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class prepare_context final {
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private:
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// Keeps names of all the bind variables. For bind variables without a name ('?'), the name is nullptr.
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// Maps bind_index -> name.
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std::vector<shared_ptr<column_identifier>> _variable_names;
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// Keeps column_specification for every bind_index. column_specification describes the name and type of this variable.
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std::vector<lw_shared_ptr<column_specification>> _variable_specs;
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// For every expression like (<target> = <bind variable>), there's a pair of (bind_index, target column_specification) in _targets.
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// Collecting all equalities of bind variables allows to determine which of the variables set the value of partition key columns.
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// The driver needs this information in order to compute the partition token and send the request to the right node.
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std::vector<std::pair<std::size_t, lw_shared_ptr<column_specification>>> _targets;
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// A list of pointers to prepared `function_call` cache ids, that
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// participate in partition key ranges computation within an LWT statement.
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std::vector<::shared_ptr<std::optional<uint8_t>>> _pk_function_calls_cache_ids;
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// The flag denoting whether the context is currently in partition key
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// processing mode (inside query restrictions AST nodes). If set to true,
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// then every `function_call` instance will be recorded in the context and
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// will be assigned an identifier, which will then be used for caching
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// the function call results.
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bool _processing_pk_restrictions = false;
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public:
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prepare_context() = default;
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size_t bound_variables_size() const;
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const std::vector<lw_shared_ptr<column_specification>>& get_variable_specifications() const &;
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std::vector<lw_shared_ptr<column_specification>> get_variable_specifications() &&;
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std::vector<uint16_t> get_partition_key_bind_indexes(const schema& schema) const;
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void add_variable_specification(int32_t bind_index, lw_shared_ptr<column_specification> spec);
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void set_bound_variables(const std::vector<shared_ptr<column_identifier>>& bind_variable_names);
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void clear_pk_function_calls_cache();
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// Record a new function call, which evaluates a partition key constraint.
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// Also automatically assigns an id to the AST node for caching purposes.
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void add_pk_function_call(cql3::expr::function_call& fn);
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// Inform the context object that it has started or ended processing the
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// partition key part of statement restrictions.
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void set_processing_pk_restrictions(bool flag) noexcept {
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_processing_pk_restrictions = flag;
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}
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bool is_processing_pk_restrictions() const noexcept {
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return _processing_pk_restrictions;
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}
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};
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}
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